Apparatus for preventing or reducing the formation of ice on the air ducts of gas turbine engines



Oct. 13, 1953 F. c1. MARCHANT ET AL 2,654,992

PREVENT APPARATUS FOR ING OR REDUCING THE FORMATION OF ICE ON THE AIR DUCTS OF GAS TURBINE ENGINES Filed March 1, 1948 Patented Oct. 13, 1953 PATENT AEPAEAmUs Fem PREVENTING R; REDUC- ING TflElEORMAQJION OF ICE ON THE AIR DUGTS OF GAS" TURBINE ENGINES Fiajiej's Qharlbs; Iver- Marchan't a'n'd Jghn" Ernest Bell; Bristbl, England, assfgfibrstoTheiBtiStbI fieropiane Go'mpany Limited; Bfisfifl; England;

a British com'pany' Thisinventiowcencerns apparatusfiifpfevent me or" reducin the fdrin'atibn of ice" on" the air duetsfdf gas turbiife engines a'ndon therij'tat ing members of the compres'sor which fb'rmsa" part of engines;

The" invention has far its objectto provide an agparatus which is applicable to gas turbines of different COhStili'b'tibfiSj the apparatus- Being readily adaptedto suit? any" partieular installa= ti'o'n.

Anether" oiijeet is to provide an a paratus which will ecdnomieallif deal with a* Wide range o'fiicihg" conditidns anii which is regulated in a simple manner for this purpose:

Acbdrdifig ly; the present invention is ch'arae' te'ri'sed i'nthat hot" gases" are generated in a" co'mbastion charfiher separate from the gas" t'urkiine e'ng-meby burning the? in a stream of an de livered to the chamber from the compres'Sbr" 0f the engine; said gas'sheifi'g discharged intbthe air entering the intake;

According to one feature of this inv'e'ntibn' ap'-- paratus f'oipie'v'er iti"rig o'r rediibing the for-met tibn of ice o'xT-the airchictsofgastilrlriiiie engines cijnn'ptises a3- heatef, separate fibm" the ehgine, which rec'eivelsah for comhustiiin froth thecom pr'essor' of the turbine engine-and in'- whichfiiei ishurnt; and means-fer conveying hdfigases-frbiif the Heater and discharging them inth the aii' going throughthe" alt ihta'le'.

According teanotfier'feature oftriis invention" the apparatus cen'iprisesa" heater; separate fiotfi" the engine, means fei 'onveyihg ai'r fidm' theeom'pr'es'ser' of the turbine engine to the" Heat e'r, means for supplying fuel" twthe heater; means fQfcdnVeyih'ghbfigase's fiiini the heater,-a'*manifoldswimmin t e intale'-' of the engine and to=- which the" hot gases are cohve'yed and means for discharging" s'ai li'otgases item the mani'fdlfl tG-Withii'i the affintake';

The fuel fer the heater is piefe'rabl'i di'awh from the supply pfovi'ded fer dperatidn" ofthe turbine ellg irieby" a purhlj; the-delivery of wh is under th'e-e'ent'rel of 'thejp'l'ie'ratbi s'o th" 1 anti-wing" efi-"ect niay be ad jhste'zf b' y vart m th quantity of fuel passing to the heater. Alte'- 1 tively or" additionally;v the anti-icing effect. ma be vaJried by manually adjusting the quantity 'dfi air: passing to the heateri the an may be conti-dlled by avawe -between the 'c'mpi essiii' and the heater. In the case of an axial fid'w 66mpres'so'r the e'ori'tiof may ce'mpfi'se one or more valves (fdr example poppet vaivesf meate'eat various stages of the"e0mpres'ss6r andreg-ulatihg maticaliy c'entrofledeig. depehding upertamhieht temperature.

In order that the nature of the invehtibh niay be lietter understb'dd a praet'ical application thereof will"now be deserihed, merelwby'way of e'giamp'le; with reference to" the aecempanyihg drawing" whereof:

Figure 1 is a purely sehe'm'atie layout of ah": para t'i-i'sih a'c'corxian'cewith the present inveiitibn, and

Referring first of a l-fte -Fighfefiitheae'roplane (not shown) has" i'n each Wing 95 bwer plant which cUmpi'is'esapaii' of gas turhiheefigihesqW ihg" side b side and sampled tegetner" te diiv'e a dounter rotatifig' pt eliee assemb1y.- Each tar"- bineeng'in'e of the ewer'maflt cempri'se's a cent press'or assembly a plurality of cdinbiistiefi chambers B whi'eit reeeives=air del iveretl lay-"the compressor a'sse'rhhl'y and in which i e1 is biirht and a turbine 1 through which the prodaets of combustion pass.

eempresser assembly- 5 comprises lawpreSsure== ax'ia-F compressor 2; which delivers it a high-pres ure ceI'iti-if gal compresser 9 the latter'in tin'ndelivers til-the cemtusuen chamber 6? Each turbine"! drii e's acempressoaasseratly'by afishait whicl'i exten'ds from the tur-binetorwam mto'wa'rde the compre'sse'ra Each" turbine also dfives ear that m th reugha titan'smissien ear:-

The turbines are" c uplecfitdgetiiee' through the ear x re and the latter transmits" drive 6ereduction geaflng centaihed witninthe hjousihg I23 The power plant buried the" wing and the" the leadin edgedf thewing. The oiieni'ng It" is located behiiid' the propeller" seas fie take em vantage of the effect ther'e'eff Although the exhaust gases from the turl'ii'ne 1" (161113 be-use'd asa" soureeof Heat tb -prevent 'the formation of ice on its associated intake IS the pressure of the gases relatively to the air pressure in duct l5 normally precludes this.

The present invention provides an apparatus to reduce or prevent the formation of ice, the apparatus being capable of use with gas turbine engines of different constructions and being readily adapted to suit any particular installation of power plant. Figure 2 shows the adaptation of the apparatus to the power plant de scribed above.

Referring to this figure and to Figure 1 of the drawings: the apparatus comprises a heater or combustion chamber l8 which is connected by a pipe [9 with the axial compressor 8. Air under pressure may flow from the compressor 8 by pipe 19 to the heater [8. To regulate the quantity of air passing from the compressor to the heater there is provided a butterfly valve 20. The valve 20 is connected by a lever mechanism diagrammatically indicated at 2| with a control lever 22 mounted in the pilots cockpit. The pilot may therefore adjust the quantity of air passing to the heater l8.

Fuel is supplied to the heater [3 by a pump 23 which is driven by an electric motor 24 connected in series with a battery 25 (for instance, the aircraft battery) and with a variable resistance 26. The pump draws fuel by a pipe 2! from the tank 28. The pump 23 delivers to heater [8 by a pipe 36. This tank contains the fuel for the operation of the gas turbine engines. The fuel is withdrawn from the tank 28 through a pipe 29 by a pump 30 and delivered to a ring 3| which is connected by branches 32 with each of the combustion chambers 6.

The adjustable arm 33 of the resistance 26 is connected as at 34 with a control lever 35 which is mounted within the cockpit of the aeroplane. By adjusting the lever 35 the resistance in the circuit of the motor 24 is varied and as a consequence the delivery of the pump 23 is adjusted.

With the foregoing arrangement it will be clear that the quantity of fuel and of air entering the heater [8 may be adjusted to suit any flight conditions.

The hot gases generated in the heater l8 are conveyed along a pipe 31 to an elliptical manifold 38. The elliptical manifold 38 is hollow and defines the mouth of the air intake I5 so that the air passing into the intake must first of all flow through the manifold 35. The inner surface of the manifold 38 is provided with a plurality of jets 39 which face inwardly of the intake Hi. The jets in the preferred arrangement take the form of long narrow slits so designed and disposed on manifold 38 as to direct ribbons of hot gas into the intake in such a way that the ribbons intermingle with the air with the minimum possible turbulence. The slits should also result in the least possible aerodynamic interference with the air flow through duct I5 when heating is not required. Moreover, the slits do not tend to soot up so readily as small circular jets.

With the arrangement described hot gases from the heater I8 pass into the manifold 38 which therefore becomes heated. The gases are discharged from the manifold 38, after heating it, through the nozzles 39 at a high velocity and towards the centre of the intake l5. As a consequence the hot gases mingle with the air flowing along the intake l5 towards the compressor assembly 5. It will be appreciated, therefore, that with the arrangement described a two-fold 4 heating effect is obtained, that is, firstly by heating the manifold 38 and, secondly, by ejecting the hot gases into the air stream.

As stated above the heating effect is varied by varying the fuel delivered by the pump and the quantity of air delivered to the heater by the compressor; with this arrangement the apparatus is under the direct control of the pilot. Since it makes use of the fuel supply for the power plant, duplication of storage tanks, pipe lines and so on is reduced to a minimum so that the apparatus is of small weight.

As is clear from Figure 2 the heater is disposed adjacent the air intake so that the apparatus operates at a high efficiency. Furthermore, with the apparatus described the temperature of the gases delivered by the heater may be in excess of the temperature of the working medium in the gas turbine engine I. The latter commonly operates at about 350 C. so that if the exhaust gases from the turbine are used for antiicing the effect is limited by this temperature.

In the installation described with reference to Figure 2 in which a pair of gas turbine engines are coupled together, there is preferably provided a separate air intake 15 for each engine. There is also associated with each intake a heating apparatus as above described. In such an arrangement means is preferably provided to interconnect the heating apparatus so as to ensure that in the event of a breakdown of one such apparatus the other may be used to heat both air intakes. Furthermore, in the event that one turbine engine is put out of useas may be done by the pilot during cruising of the aeroplanethe heating apparatus of the other power plant may be used to prevent or reduce the ice formation on the airintake of the inoperative engine.

It will be appreciated that the heater may be used, instead of, or additionally to heating the air duct l5, for heating other air ducts on the aeroplane or even for heating the wings themselves to prevent or reduce the formation of ice thereon. For instance, the air intake 40 to an oil cooler 4|. In any such application of the invention the temperature of the gases will be suitably selected so that ice cannot form at any part along the length of the air passageway lying downstream from the manifold. It is to be understood that the manifold may be disposed so as to produce a heating effect at any part along the length of the air duct and that the invention is not limited to the production of this effect at the inlet throat alone.

An important advantage of the apparatus de-. scribed lies in the ability to draw air from that stage of the compressor which will provide the minimum pressure necessary for the satisfactory operation of the apparatus. This means that the work expended in compressing air for the apparatus will be as low as is possible. The greater power expended in providing greater pressures than those indicated above will not necessarily be usefully recovered in the apparatus.

The expression anti-icing as used throughout the specification and claims includes the removal of ice already formed on a surface and the prevention of such ice formation at all.

We claim:

1. A gas turbine engine comprising a compressor, a duct conveying atmospheric air to the compressor, combustion equipment which receives air from the compressor and in which fuel is burnt, a turbine driven by the products of combustion and driving the compressor, a combustion chamber, separate of the engine combustion equipment, a pipe to carry air only from the engine compressor to said combustion chamber, means for supplying and burning fuel in said combustion chamber and a conduit to convey the combustion gases from said chamber to said duct and for discharging said gases into the stream of air passing through the duct.

2. A gas turbine engine comprising a compressor, a duct conveying atmospheric air to the compressor, combustion equipment which receives air from the compressor and in which fuel is burnt, a turbine driven by the products of combustion and driving the compressor, a combustion chamber, separate of the engine combustion equipment, a pipe to convey air only from the engine compressor to said combustion chamber, means for supplying and burning fuel in said combustion chamber, a manifold surrounding the duct and communicating therewith and a conduit to convey the combustion gases from said chamber to the manifold for discharge into the duct.

3. A gas turbine engine comprising a compressor, a duct conveying atmospheric air to the compressor, combustion equipment which receives air from the compressor, a fuel system to deliver fuel to the combustion equipment, a turbine driven by the products of combustion and driving the compressor, a combustion chamber, separate of the engine combustion equipment, a pipe to convey air from the engine compressor to said combustion chamber, a pump separate of the engine fuel system for delivering fuel therefrom to the combustion chamber, means for controlling the pump delivery, and a conduit to convey the combustion gases from said chamber to said duct and for discharging said gases into the stream of air passing through the duct.

4. A gas turbine engine according to claim 3 wherein an adjustable valve is provided to control the quantity of air passing from the compressor to the combustion chamber.

5. A gas turbine engine comprising a compressor, a duct conveying atmospheric air to the compressor, combustion equipment including a combustion chamber which receives air from the compressor and in which fuel is burnt, a turbine driven by the products of combustion from said combustion chamber and driving the compressor, a combustion chamber independent of and separate from the combustion chamber of the engine combustion equipment, a pipe to carry air from the engine compressor to said independent combustion chamber, means for supplying and burning fuel in said independent combustion chamber, and a conduit to convey the combustion gases from said independent chamber to said duct and for discharging said gases into the stream of air passing through the duct.

6. A gas turbine engine comprising interconnected low pressure and high pressure compressors, a duct conveying air to the low pressure compressor, combustion equipment comprising a combustion chamber which receives air from the high pressure compressor, a fuel system to deliver fuel to the combustion equipment, a turbine for receiving the products of combustion from said combustion equipment and driven thereby and driving the compressors, a combustion chamber independent of and separate from the combustion chamber of the engine combustion equipment, a pipe communicating with said low pressure compressor and said independent combustion chamber to convey air from the low pressure compressor to said independent combustion chamber, a pump separate of the engine fuel system for delivering fuel therefrom to said independent combustion chamber, means for controlling the pump delivery, a conduit to convey the combustion gases from said independent chamber to said duct and for discharging said gases into the stream of air passing through the duct, and valve means for controlling the supply of air from the low pressure compressor to said independent chamber.

FRANCIS CHARLES IVOR MARCHANT. JOHN ERNEST BELL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,924,122 Jone Aug. 29, 1933 2,327,202 McCollum Aug. 17, 1943 2,357,112 Heymann Aug. 29, 1944 2,393,792 McCollum Jan. 26, 1946 2,399,046 Larrecq Apr. 23, 1946 2,404,275 Clark July 16, 1946 2,409,177 Alien Oct. 15, 1946 2,411,227 Planiol Nov. 19, 1946 2,425,630 McCollum Aug. 12, 1947 2,435,990 Weiler Feb. 17, 1948 2,469,375 Flagle May 10, 1949 

